question_answer

The number of types of bonds between two carbon atoms in calcium carbide is:     AIEEE  Solved  Paper (Held On 11 May  2011) 

A)  One sigma, one pi                     

B)  Two sigma, one pi

C)  Two sigma, two pi                      

D)  One sigma, two pi

Correct Answer: D

Solution :

                                Calcium carbide exists as \[C{{a}^{2+}}\]and \[C{{a}_{2}}^{2-}.\]According to the molecular orbital model, \[{{C}_{2}}^{2-}\]should have a bond order of 3 (configuration \[\pi _{u}^{2}\pi _{u}^{2}\sigma _{g}^{2}\]). MOT configuration suggests that it contains one o and two